Diesel fuel is a refined petroleum product which historically has been burned in the engines powering most of the world's trains, ships, and large trucks. More recently, engines that burn diesel fuel have been adapted for use in light weight trucks and automobiles. Petroleum, from which diesel fuel is derived, is a non-renewable resource of finite supply. Acute shortages and dramatic price increases in petroleum and the refined products derived from petroleum have created the need to find alternative fuels. Moreover, diesel engines undesirably emit relatively high levels of certain pollutants, especially particulates. Accordingly, extensive research effort has focused on replacing some or all petroleum-based diesel fuel with a cleaner-burning fuel derived from a renewable source such as farm crops.
Biodiesel is the name for a variety of ester-based oxygenated fuels made from vegetable oils, fats, greases, or other sources of triglycerides. Biodiesel is a nontoxic and biodegradable substitute and supplement for petroleum diesel. Even in blends as low as 20% biodiesel to 80% petroleum diesel (B20), biodiesel can substantially reduce the emission levels and toxicity of diesel exhaust. Biodiesel has been designated as an alternative fuel by the United States Department of Energy and the United States Department of Transportation, and is registered with the United States Environmental Protection Agency (US EPA) as a fuel and fuel additive. Low blend concentrations of biodiesel (below 20%) can generally be used in any diesel engine, without the need for mechanical alterations, and is compatible with existing petroleum distribution infrastructure. For higher blends, typical modifications to diesel engines involve replacement of rubber fuel hoses and pump seals with a compatible elastomer.
Made from virgin or used vegetable oils and animal fats, biodiesel is methyl or ethyl esters of fatty acid. Although the US EPA has registered biodiesel as a fuel and fuel additive, currently there is no official tracking of biodiesel. The development, production and use of biodiesel are encouraged as a renewable energy source by tax incentives. In order to verify whether a given fuel blend is a biodiesel or qualifies as a biodiesel (for example for tax incentive qualification) it is necessary to quickly screen fuel blends to confirm the presence or absence of biodiesel.
Many countries, including the United States are advocating the use of biodiesel and are actively employing nearby resources to use for such purposes. Indiana, for example, can provide ample soy oil, whereas Thailand uses palm oil and Ireland uses frying oil and animal fats. Although the relative amounts vary, there are only five fatty acid chains that are common in most vegetable oils and animal fats. To be used as fuel, these fatty acids are chemically reacted (transesterified) with an alcohol, in the presence of a catalyst resulting in the formation of methyl or ethyl esters and glycerol. Used oils are can also be included in biodiesel but require more rigorous cleanup. Quality is essential for proper performance of the fuel with no damage to the engine. While an engine can be designed for 100% biodiesel, existing engines only tolerate from 5-20% biodiesel blends without modification or reduction in engine efficiency, although long-term use of biodiesel in engine research is still being studied.
In addition to being able to tell if a given quantity of fuel is a biodiesel for purposes of monitoring tax credit incentives, it is also important for someone purchasing a fuel to be able to confirm whether it is biodiesel or not, especially if one is paying a premium for biodiesel.
The present invention provides a simple colorimetric screening test to determine whether or a fuel contains biodiesel.